Worldwide eradication of malaria, man's most deadly killer, is presently not attainable. Drug-resistant parasite strains and mosquito resistance to the insecticides are now common. An antimalarial vaccine does not exist and biochemical studies on the blood stages of the parasite have been limited because techniques for the mass isolation of these developmental forms viz., merozoite and trophozoite, are undescribed. The proposed research will develop methods for the preparation of Plasmodium lophurae and P. knowlesi trophosoites and merozoites in such yield and purity that exploration of their structural and functional properties will be possible. Merozoites will be harvested by filtration, density gradient and isopycnic centrifugation; purity will be evaluated by phase contrast and electron microscopy as well as chemical markers. Trophozoites will be isolated by immune lysis, ultrasound and AnCl2; purification will be by isopycnic and differential centrifugation; purity will be quantified by iodinating red cells prior to isolation and evaluating label in the trophozoite fractions. The membrane proteins of the trophozoite, merozoite and the red blood cell will be studied. The rationale for such studies is based on the premise that specific information on membrane structure will lead to a more complete understanding of the interactions that take place at the parasite interface--the boundary separating the plasmodium from the host milieu. Characterization of the outer trophozoite membrane will be made by electron microscopy to determine ferritin-conjugated phyto-hemagglutinin and influenza virus binding. Surface membranes will be isolated by homogenization and purification accomplished by centrifugation; protein characterization will be by polyacrylamied gel electrophoresis in SDS; isotopic markers will be used to distinguish surface proteins of the erythrocyte from other membrane proteins. To study the biosynthesis of parasite membranes, trophozoite and schizont infected cells will be incubated in vitro with radioisotope and membrane proteins isolated and identified by PAGE-SDS, and liquid scintillation spectrometry.